Category Archives: animal attack

Noodling and You

Today’s article came suggested by a reader, so thanks Dan. If anyone else has any topics or articles they’d like covered, feel free to email me or hit me up on twitter.

Noodling, for those who haven’t seen the tv shows, is the practice of fishing using just your hands. Typically used on catfish, it involves putting your hand into holes where the fish typically dwell. The fish then bites the noodler’s hand or hands, usually in a defensive manner. This allows the fisher to grasp the fish and hopefully pull in the catch while it spins to try to release itself. If successful, then the fisherman gets to figure out how to remove his or her hand from the fish’s mouth.

It doesn’t take a lot of imagination to come up with numerous types of injuries the fisher can receive during this activity. The article itself describes a case report of multiple extensor injuries on the arm of a 14-year-old patient secondary to the bite of a 60 lb catfish. He did well, but serves as a good example of the forces involved from such large fish. And that’s not even mentioning the envenomations that can be received from the spines on the dorsal and pectoral fins, or the infections possible from the environment in which the injuries are received.

The recommendations for management of noodling injuries are reasonable. Sure, they should be examined carefully for neurovascular compromise, as well as structural injuries, like any other animal attack.Always consider imaging for suspected foreign bodies. If horned, hot water is best, like most if not all marine envenomation syndromes. I do like that they recommend early protected mobilization to decrease freezing of joints. 

Then they go and recommend leaving wounds open to heal by secondary intention or delayed primary. With adequate irrigation, I would argue they can be closed primarily if no significant crush injury is noted. At least they don’t recommend using “loose closure” or anything else that isn’t useful. The need for surgical specialties for tendon or deep muscle injuries is not particularly earth shattering, but some may need to be reminded. As always, give the lifesaving tetanus prophylaxis and use antibiotics that cover gram negatives as well as gram positives.

Sure, nothing terribly new described in the for most marine or freshwater injuries, but still a pretty good article.

Catfish noodling forearm injury requiring urgent surgical treatment: a case report and review of the literature.
http://www.ncbi.nlm.nih.gov/pubmed/24412658

How to survive a shark attack?

The easy answer is to stay out of the water. That takes all the fun out of life though, so there has to be a better answer. Sadly, once a shark has decided to attack, your chances of survival drastically decrease. Nature’s evolutionary killing machine is very good at its job, and even if you’re just injured, it’s usually not pretty. And the number of unprovoked attacks in Australia has increased significantly in the last 20 years, with 2000-2009 having nearly 3 times as many attacks as the decade from 1980-1989. Don’t think that your next beach trip will be a scene right out of JAWS though, as there are still only ~12 attacks per year in ‘Straya, and ~1 death per year. So how do you go about avoiding an attack? Based on this paper, there are differences in geography, season, and human behavior that might make a difference. Anything that can trend this number back down will make watersports safer. 

Certainly, the sharks historically known as dangerous are the ones to worry about. The white, bull, and tiger shark are the only species identified to cause fatalities in the last 20 years. All of those were from sharks longer than 2m as well. but don’t let the smaller ones fool you. The smallest shark involved in an incident was merely 0.4m long. Juvenile whites can be mistaken for whaler species, and a smaller bite doesn’t always mean a safer one. Wobbegong sharks have also been recorded as causing injuries. However, the white shark is still the most dangerous, comprising less than 1/3 of the attacks, but more than 2/3 of the fatalities.

The simple geographic answer is “don’t swim where the sharks are.” Well, that’s tough to do in Australia, where sharks have been seen swimming down the street after floods. The figure below shows the location of the 592 recorded unprovoked incidents over the 218 year span they’ve been keeping records. However, it there are safe spots. Many beaches in well populated areas have shark-control programs. I won’t get into the ethics behind culling, but the shark nets seem to be effective, and certainly are a simple method to cut attacks. However, as demonstrated in the article, people are moving and recreating in areas without shark-control in increasing numbers, and the number of attacks has gone up as the population grows into those areas. Also, the increase in watersports in brackish water has increased the number of attacks that are related to bull sharks. 

sharks

It is also often stated that being in the water at dawn and dusk increases your risk of attack. Well, based on the data in this paper, it can’t be proven or disproven. The overwhelming majority of cases occur from 7am to 8pm, but they don’t break down times down to seasons, so you can’t determine attacks based on sunrise and sunset.

Is there a seasonal variation then? Most attacks occur in the summer, but that’s when most people are in the water, so that’s not helpful. Sharks do show migratory patterns following their prey, and warmer water months still have more attacks. There has been an increase in cold water attacks though, as people are starting to don wetsuits to spend more time in the water. 49% of attacks in the last twenty years have been on people wearing a wetsuit. This is an interesting statistic, because the rates of attacks while diving have stayed stable, but the rates for attacks while surfing nearly doubled from preceding period. 

One important behavior that has been shown to increase the likelihood of an attack is being near their natural prey. Schools of fish slightly increase risks, but being near seals dramatically increases being attacked. So if you’ve got the option, don’t surf, swim, or dive near seal colonies. 

Victims were only aware of a shark in the vicinity about 20% of the time, so keeping an eye out may be of some use. Don’t expect much of a warning, either, as sharks “bumped” or swam very close to a victim before an attack only 14% of the time.

Unfortunately, there isn’t one simple answer on how to survive a shark attack.  Less than 10% of the incidents report fighting back. Gouging the eyes, hitting the gills, or shoving things in the mouth may help though, as it made the shark stop or leave about 2/3 of the time. I can’t imagine that nobody fought back in the other cases, so this is another area where the data isn’t definitive.

Still, as explained in the paper, you are more than 80 times more likely to drown than to die from a shark attack. The risks are still extremely low, but taking a few safety measures can make them even lower.

Changing patterns of shark attacks in Australian waters
http://www.publish.csiro.au/?paper=MF10181

Is candiru really the scourge of the Amazon?

Photograph by Max Gibbs, Getty Images

Ah the candiru. A little fish of legend. Is it really something to be scared of? I mean, look at the little guy.  Well, this review article will probably answer that question for you.

Who hasn’t heard the stories about fish swimming up urine streams to get lodged in the urethrae of unsuspecting tourists? If you ask all of your medical friends, I bet greater than 75% of them have heard of stories, and some may anecdotally report being present for extractions. Even nonmedical acquaintances are likely to have heard these stories. So where did they come from?

First encountered verbally by Amazon explorers, written evidence of this mythical creature was first published in 1829 by Carl Friedrich Philipp von Martius (names were better back then). He of course never actually saw one, and never saw the preventive method of tying a ligature around one’s penis either. But by putting it in writing, it now became fact. So much so, it has  been repeated over the last 180+ years by multiple sources, and in modern-day has been reported by such reputable sources as River MonstersGrey’s AnatomyDr. Oz, and Weird Planet.

As reported in the review article, the early explorers likely weren’t even all talking about the same fish. Something that small probably evaded most detailed examinations at the time, and lack of good preservation meant most specimens were pretty chewed up in the lab. Add to the fact that they were effectively playing a giant game of telephone with the natives, since there was very little in the way of common language between all the tribes. Lots of pantomiming and hand gestures that could be misinterpreted, as well as simple syntax problems likely caused mistranslations about most things.

With this much plurality of anecdote, it has to be fact at this point, right? Well, sorry to burst your bubble, but no. Even the best documented case from 1997 has serious problems with evidence. The fish that is reported as the source was much too large (11.5mm in diameter!) to enter the urethra of the patient, and the report has it jumping out of the water, or swimming up the stream, as it were. The report also has the fish being attracted to urine. Also, the specimen fish still had spines in place, which had been snipped off in the report of the surgery. The marine biologist who went down to examine the evidence came away with reservations about the report.

Here is a list of “facts” about candiru that are myths

  • They are attracted to urine. Experiments have shown this isn’t true, they hunt by sight
  • They can swim up a stream out of the water. Physics applies to all fish, even small ones.
  • There is documented evidence of urethral invasion. The sparse case reports available do not seem to be valid.

If you want to be cautious, you can simply wear a bathing suit in the water, but that’s more for modesty than for safety. There simply does not appear to be any evidence that this is a problem. The review article searched for literature in many languages and even did a deep dive into the historical data, and came away wanting.

In the end, it was probably just a way for the natives to tell the explorers, “Hey, you guys, stop peeing in our river, we bathe, drink, and get food from there.” It simply snowballed from there.

But hey, who lets facts get in the way of a good story.

Candiru—A Little Fish With Bad Habits: Need Travel Health Professionals Worry? A Review
http://www.ncbi.nlm.nih.gov/pubmed/23464720